A1 Refereed original research article in a scientific journal
Nitric oxide represses photosystem II and NDH-1 in the cyanobacterium Synechocystis sp PCC 6803
Authors: Solymosi Daniel, Shevela Dmitry, Allahverdiyeva Yagut
Publisher: Elsevier BV
Publication year: 2022
Journal: BBA - Bioenergetics
Journal name in source: Biochimica et biophysica acta. Bioenergetics
Journal acronym: Biochim Biophys Acta Bioenerg
Article number: 148507
Volume: 1863
Issue: 1
ISSN: 0005-2728
eISSN: 1879-2650
DOI: https://doi.org/10.1016/j.bbabio.2021.148507
Self-archived copy’s web address: https://research.utu.fi/converis/portal/detail/Publication/67645947
Photosynthetic electron transfer comprises a series of light-induced redox reactions catalysed by multiprotein machinery in the thylakoid. These protein complexes possess cofactors susceptible to redox modifications by reactive small molecules. The gaseous radical nitric oxide (NO), a key signalling molecule in green algae and plants, has earlier been shown to bind to Photosystem (PS) II and obstruct electron transfer in plants. The effects of NO on cyanobacterial bioenergetics however, have long remained obscure. In this study, we exposed the model cyanobacterium Synechocystis sp. PCC 6803 to NO under anoxic conditions and followed changes in whole-cell fluorescence and oxidoreduction of P700 in vivo. Our results demonstrate that NO blocks photosynthetic electron transfer in cells by repressing PSII, PSI, and likely the NDH dehydrogenase-like complex 1 (NDH-1). We propose that iron‑sulfur clusters of NDH-1 complex may be affected by NO to such an extent that ferredoxin-derived electron injection to the plastoquinone pool, and thus cyclic electron transfer, may be inhibited. These findings reveal the profound effects of NO on Synechocystis cells and demonstrate the importance of controlled NO homeostasis in cyanobacteria.
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